Tiny Desert Fish Saved: 20 to 77 in One Year

When the population of Earth's rarest fish dropped to just 20 individuals, scientists knew they had to act fast or watch a species disappear forever.

The Devils Hole pupfish lives in exactly one place on the planet: a scorching hot pool at the bottom of a desert cavern in Death Valley National Park. For thousands of years, these shimmering blue fish have somehow survived in 93-degree water that's dangerously low in oxygen and nutrients.

Last year, something went wrong. The population that had reached 212 fish in fall 2024 suddenly plummeted to just 20.

Biologists Olin Feuerbacher and Michael Schwemm with the U.S. Fish and Wildlife Service made a historic decision. For the first time ever, they would release captive-bred pupfish into Devils Hole from their backup population.

Since 2013, scientists have been raising insurance pupfish in a 100,000-gallon tank built to perfectly replicate the cavern. They'd hoped never to need this emergency option, but with only 20 fish left, waiting wasn't possible.

The team released 19 captive-bred fish first, then added about 50 more. This spring, counters spotted 77 pupfish darting through the rocky pool.

"We're breathing a lot easier at 77 than 20," says Feuerbacher, who has worked with the species for nearly two decades. Schwemm is even more direct: "I think we saved the species."

The Bright Side

The Devils Hole pupfish has beaten incredible odds before. Its population dropped to just 35 fish back in 2013, yet it bounced back to over 200.

Scientists have spent decades protecting this tiny survivor, monitoring it twice yearly and even adding supplemental food to its nutrient-poor water since 2007. The backup breeding program they started in 2013 proved its worth when crisis struck.

Kevin Wilson, a supervisory biologist at Death Valley National Park, notes that Devils Hole is "probably the smallest known habitat for a vertebrate species." Yet this fish keeps defying expectations, thriving in conditions that would kill most other creatures.

The pupfish's comeback shows what's possible when conservationists refuse to give up on a species, no matter how slim its chances seem. From the brink of extinction to a growing population in just months, these resilient little fish are swimming proof that hope and quick action can turn a crisis around.